Flap antenna

ABSTRACT

An elongated waveguide antenna is mounted on an aircraft in a position normally out of the way and inoperable when the aircraft is in conventional flight so as not to interfere with other components. However, when the aircraft is approaching for a landing wherein certain control surfaces such as landing flaps are in lower positions, the antenna on the aircraft is exposed in a position that the beam pattern from the antenna is directed forwardly generally towards the horizon and downwardly from the horizon. In one embodiment, the antenna is located in the trailing edge flap of a wing, lowering of the flap then properly positioning the antenna so that the ground can be scanned during landing approach. In a second embodiment the antenna is located in the leading edge of a wing behind a normal leading edge wing flap, lowering of the edge wing flap then exposing the antenna for directing its beam properly for a landing approach. These installations would be useless for conventional airborne radar.

tates Patent [191 Young [4 1 Feb. 25, 1975 FLAP ANTENNA [76] Inventor: David W. Young, 627 N.

Beachwood Drive, Burbank, Calif. .1506

[22] Filed: Apr. 27, 1973 21 Appl. No.: 355,065

[52] US. Cl 343/708, 343/772, 343/775, 343/789 [51] Int. CL... H0lq l/28, HOlq 13/00, HOlq 19/10 [58] Field of Search 343/705, 708, 711-713, 343/771, 772, 775, 789

[56] References Cited UNITED STATES PATENTS 2,636,987 4/1953 Dome 343/771 X 3,390,393 6/1968 Upton 343/708 3,662,392 5/1972 Stapleton et a1 343/708 FOREIGN PATENTS OR APPLICATIONS 747,905 10/1944 Germany 343/708 Primary Examiner-Eli Lieberman Assistant Examiner-Marvin Nussbaum Attorney, Agent, or Firm-Ralph B. Pastoriza; John E. Kelly [57] ABSTRACT An elongated waveguide antenna is mounted on an aircraft in a position normally out of the way and inoperable when the aircraft is in conventional flight so as not to interfere with other components. However, when the aircraft is approaching for a landing wherein certain control surfaces such as landing flaps are in lower positions, the antenna on the aircraft is exposed in a position that the beam pattern from the antenna is directed forwardly generally towards the horizon and downwardly from the horizon. In one embodiment. the antenna is located in the trailing edge flap of a wing, lowering of the flap then properly positioning the antenna so that the ground can be scanned during landing approach. in a second embodiment the an tenna is located in the leading edge of a wing behind a normal leading edge wing flap, lowering of the edge wing flap then exposing the antenna for directing its beam properly for a landing approach. These installations would be useless for conventional airborne radar.

5 Claims, 5 Drawing Figures 1 FLAP ANTENNA This invention relates to antennas used on aircraft and more particularly to a radar waveguide antenna in combination with a structural portion of an aircraft for use specifically during approach to landing and actual landing.

BACKGROUND OF THE INVENTION Airborne radars capable of looking in a forward direction usually have their antennas mounted on leading edge surfaces of the aircraft. For example, weather radar and fire control radar antennas are usually mounted in the nose. In the case of elongated waveguide type antennas as used for scanning, the leading edge of the wing has been used except in the case of large jet planes having leading edge wing flaps.

In my co-pending patent application Ser. No. 353,201 filed Apr. 20, 1973, now U.S. Pat. No. 3,829,862, entitled RIDGE SCAN ANTENNA there is disclosed an elongated waveguide antenna mounted in the leading edge of an aircraft wing. This scanning antenna is particularly useful during landing approaches and in this respect, the leading edge portion of the wing is an ideal location since for almost all aircraft it presents a very long surface capable of accomodating the elongated waveguide. This surface can be seen in line of sight from the horizon along the center line of the aircraft.

In another of my co-pending patent applications Ser. No. 355,019 filed Apr. 27, 1973 entitled SHADOW ANTENNA, there is disclosed the use of the high T tail characteristic of some larger jet aircraft for mounting an elongated waveguide type antenna.

There are many aircraft which do not have the high T tail and also wherein the leading edge of the wing was not always thought to be available because of the presence of leading edge flaps. The problem thus presents itself to find a fairly long straight surface on an aircraft which can be seen in line of sight from the horizon along the center line of aircraft but which surface is not already used for other radar such as fire control and weather radars. Such surface should not only be considerably longer than the diameters of most radomes, but also should not have to be de-iced.

BRIEF DESCRIPTION OF THE PRESENT INVENTION In accord with the present invention, an elongated waveguide type antenna is mounted on a structural portion of the aircraft which would not otherwise normally be used for an antenna. More particularly, since the waveguide antenna to be mounted is only used on landing approaches, the antenna aperture need not meet the requirement ofline of sight from the horizon during conventional operation of the aircraft but only during landing approaches. It therefore becomes feasible to mount the antenna in a wing flap which assumes a lowered position during landing approach, the arrangement being such that when the flap is in this lowered position, the antenna incorporated therein is properly positioned to direct a beam in a forward direction towards the horizon and in a downward direction from the horizon.

The advantage ofthe foregoing combination of waveguide antenna and wing flap is the fact that the antenna can be easily installed, replaced, or serviced by simply removing the flap from the remaining portion of the aircraft wing. Moreover, there are no problems of interference with de-icing mechanism, since no de-icing of the flap is required.

In a second embodiment of the invention, the antenna is mounted in the leading edge portion of those aircraft wings incorporating a front landing flap so that antenna aperture is normally covered by the flap during conventional flight operations but it is exposed when the front flap is lowered during landing approaches. In these types of aircraft, de-icing mechanism is usually incorporated in the front landing flap itself so again there is no interference and a relatively long straight line surface is available.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of the invention will be had by now referring to the accompanying drawings in which:

FIG. 1 is a perspective view of an aircraft on a landing approach showing a wing flap .in a lowered position preparatory to landing incorporating the waveguide antenna of the present invention;

FIG. 2 is an enlarged fragmentary cross section of the flap and trailing edge portion of the wing taken in the direction of the arrows 2--2 of FIG. 1;

FIG. 3 is an enlarged fragmentary cross section of the antenna itself incorporated in the flap as shown in FIG.

FIG. 4 is a fragmentary section of a flap showing a modified antenna placement arrangement; and,

FIG. 5 shows a wing with a leading edge flap wherein the antenna is incorporated in the leading edge surface of the wing.

DETAILED DESCRIPTION OF THE INVENTION Referring first to FIG. 1 there is shown an aircraft having a wing 11 with its landing flap 12 in a down position preparatory to landing. An elongated waveguide aperture is indicated at 13 in the flap l2 and when the flap is in its lowered position shown, the radiated beam from the antenna is directed generally towards the horizon and downwardly from the horizon as indicated by the general fan shaped beam 14.

Referring to FIG. 2, the antenna itself is shown in end view at 15 and may constitute a ridge scan antenna such as shown and described in certain embodiments of my referred to co-pending patent application. Means for passing electromagnetic energy into one end of the waveguide antenna is indicated by the dashed branch waveguide portion 16 passing from a rotary joint 17 at the pivot of the flap 12.

Referring to FIG. 3, further details of the antenna are illustrated. Thus, the waveguide 15 has a series of holes 18 dimensioned below cut-off so as to be non-resonant in a broad side wall to one side of the center line of the wall. A metallic flange portion 19 in turn extends normally from the edge of the broad side wall adjacent to the holes. This flange has a roughened surface 20 which functions to narrow the beam pattern in a plane perpendicular to the axis of the antenna.

In FIGS. 2 and 3, the antenna is disposed in the flap in a position spaced rearwardly from the pivot point of the flap a sufficient distance such that the beam radiated from the antenna is directed forwardly towards the horizon and downwardly from the horizon when the flap is in its lowered position as shown. In smaller aircraft, it may be desirable to locate the waveguide antenna itself much closer to the pivot point for the flap for dynamic balancing reasons. In this event, an arrangement as shown in FIG. 4 may be used.

With specific reference to FIG. 4, there is shown a wing 21 having a wing flap 22 incorporating a ridge scan waveguide antenna 23 disposed adjacent to the pivot point for the flap. As in the case of the antenna of FIG. 3, there is provided a metallic flange portion with a roughened surface 24 to narrow the beam in a plane perpendicular to the axis of the waveguide. An elongated metallic mirror 25 is disposed in the flap in a position spaced rearwardly from the pivot point of the flap to receive direct radiation from the antenna 23 and direct it forwardly generally towards the horizon and downwardly from the horizon when the flap is in its lowered position. A suitable elongated aperture or radome 26 corresponding to 13 shown in FIGS. 2 and 3 may be provided in the flap.

In the flap antenna installations of both FIGS. 2 and 4, the elevation pattern, while designed for full flap position, is broad enough to be used with reduced .flap angles.

Referring now to FIG. 5, there is shown a second embodiment of the invention wherein the antenna is located in the leading edge of a wing behind a leading edge flap. Thus as shown in fragmentary view, the leading wing edge 27 is provided with a leading edge flap 28 arranged to be retracted in flush engagement with the leading edge or to be lowered when making a landing approch. In FIG. 5 the flap 28 is shown in a lowered position.

The elongated waveguide antenna is illustrated at 29 and again may include a forwardly extending metallic flange with a roughened surface 30 for narrowing the beam in a vertical plane perpendicular to the axis of the waveguide. a radome aperture 31 is provided in the leading edge of the wing 27 as shown.

When the leading edge flap 28 is in a retracted position as during conventional flight, the aperture 31 is eclipsed. However, when the flap is in its lowered position, the radiated beam will be directed forwardly towards the horizon and downwardly from the horizon as in the case of the beam for the antenna incorporated in the trailing edge flap described heretofore.

OPERATION The operation of the aircraft antenna of this invention will be evident from the foregoing description. While the apertures for the antennas in the specific locations described are eclipsed during conventional flight, they will be exposed during a landing approach when the flap is in a lowered position. It is only during this time that the antenna is to be used and thus the present invention provides a unique combination wherein an antenna can be readily accomodated in the aircraft without interference with other antennas or mechanisms such as de-icing devices.

In the case where the antenna is located in the flap itself, it will be evident that it may readily be serviced or replaced by simply removing the flap from the remaining portion of the wing. This structure provides an enormous advantage in that it is not necessary to dismantle portions of the wing or fuselage of the aircraft in order to effect repairs or replacements of antennas.

What is claimed is:

1. In combination:

a. an elongated horizontally disposed wave guide antenna having an elongated horizontal aperture providin g a generalnarrow fan-shaped beam in a vertical plane;

b. an aircraft having a wing trailing edge landing flap control defining a long straight surface at least as long as said elongated aperture and visible to line of sight viewing from the horizon in front of the aircraft along the center line of the aircraft when the landing flap is moved to a lowered position during an approach for a landing;

0. means mounting said antenna in said landing flap in such a position that said beam pattern from said antenna is directed forwardly generally towards the horizon and downwardly from the horizon only when the long straight surface of the flap is in its lowered position during a landing approach to expose completely said elongated aperture to line of sight viewing from the horizon along the center line of the aircraft;

d. means for passing electromagnetic energy into the wave guide antenna when the flap is lowered during a landing approach, whereby the antenna can be easily installed, replaced, or serviced by simply removing the flap from the remaining portion of the aircraft wing.

2. The combination of claim 1, in which the antenna is disposed in the flap in a position spaced rearwardly from the pivot point of the flap a sufficient distance such that the beam radiated directly from the antenna is directed forwardly towards the horizon and downwardly from the horizon when the flap is in said lowered position. I

3. In combination:

a. an elongated horizontally disposed waveguide antenna having an elongated horizontal aperture providing a general narrow fan-shaped beam in a vertical plane;

b. an aircraft having a leading edge wing landing flap control defining a long straight surface atleast as long as said elongated aperture and visible to line of sight viewing from the horizon in front of the aircraft along the center line of the aircraft when the landing flap is moved to a lowered position during an approach for a landing;

c. means for mounting the antenna in the leading edge portion of the aircraft wing which only becomes exposed when said leading edge flap is lowered such that said beam pattern from said antenna is directed forwardly generally towards the horizon and downwardly from the horizon only when the long straight surface of the flap is in its lowered position during a landing approach to expose completely said elongated aperture to line of sight viewing from the horizon along the center line of the aircraft; and,

d. means for passing electromagnetic energy into the wave guide antenna when the flap is lowered during a landing approach.

4. In combination, an elongated waveguide antenna; an aircraft having a wing trailing edge landing flap control surface movable from a first to a second position when approaching for a landing; means mounting the antenna in the flap in a position adjacent to the pivot point of the flap; means for passing electromagnetic energy into one end of the waveguide antenna and an elongated metallic mirror disposed in the flap in a position spaced rearwardly from the pivot point of the flap to receive direct radiation from the antenna and direct it forwardly towards the horizon and downwardly from the horizon when the flap is lowered during a landing approach, whereby the antenna can be easily installed, replaced, or serviced by simply removing the flap from the remaining portion of the aircraft wing.

5. In combination, an elongated waveguide antenna; an aircraft having a wing landing flap control surface movable from a first to a second position when approaching for a landing; means mounting the antenna on the aircraft in such a position that the beam pattern from the antenna is directed forwardly generally to wards the horizon and downwardly from the horizon only when the flap is in a lowered position during a landing approach; and means for passing electromagnetic energy into one end of the waveguide antenna when the flap is lowered during a landing approach, said waveguide antenna having a series of holes dimensioned below cut-off so as to be non-resonant in a broad side wall to one side of the central line of the wall and a metallic flange portion extending normally from the edge of the broad side wall adjacent to the holes, said flange having a roughened surface to narrow the beam pattern in a plane perpendicular to the axis of the 

1. In combination: a. an elongated horizontally disposed wave guide antenna having an elongated horizontal aperture providing a general narrow fan-shaped beam in a vertical plane; b. an aircraft having a wing trailing edge landing flap control defining a long straight surface at least as long as said elongated aperture and visible to line of sight viewing from the horizon in front of the aircraft along the center line of the aircraft when the landing flap is moved to a lowered position during an approach for a landing; c. means mounting said antenna in said landing flap in such a position that said beam pattern from said antenna is directed forwardly generally towards the horizon and downwardly from the horizon only wHen the long straight surface of the flap is in its lowered position during a landing approach to expose completely said elongated aperture to line of sight viewing from the horizon along the center line of the aircraft; d. means for passing electromagnetic energy into the wave guide antenna when the flap is lowered during a landing approach, whereby the antenna can be easily installed, replaced, or serviced by simply removing the flap from the remaining portion of the aircraft wing.
 2. The combination of claim 1, in which the antenna is disposed in the flap in a position spaced rearwardly from the pivot point of the flap a sufficient distance such that the beam radiated directly from the antenna is directed forwardly towards the horizon and downwardly from the horizon when the flap is in said lowered position.
 3. In combination: a. an elongated horizontally disposed wave guide antenna having an elongated horizontal aperture providing a general narrow fan-shaped beam in a vertical plane; b. an aircraft having a leading edge wing landing flap control defining a long straight surface at least as long as said elongated aperture and visible to line of sight viewing from the horizon in front of the aircraft along the center line of the aircraft when the landing flap is moved to a lowered position during an approach for a landing; c. means for mounting the antenna in the leading edge portion of the aircraft wing which only becomes exposed when said leading edge flap is lowered such that said beam pattern from said antenna is directed forwardly generally towards the horizon and downwardly from the horizon only when the long straight surface of the flap is in its lowered position during a landing approach to expose completely said elongated aperture to line of sight viewing from the horizon along the center line of the aircraft; and, d. means for passing electromagnetic energy into the wave guide antenna when the flap is lowered during a landing approach.
 4. In combination, an elongated waveguide antenna; an aircraft having a wing trailing edge landing flap control surface movable from a first to a second position when approaching for a landing; means mounting the antenna in the flap in a position adjacent to the pivot point of the flap; means for passing electromagnetic energy into one end of the waveguide antenna and an elongated metallic mirror disposed in the flap in a position spaced rearwardly from the pivot point of the flap to receive direct radiation from the antenna and direct it forwardly towards the horizon and downwardly from the horizon when the flap is lowered during a landing approach, whereby the antenna can be easily installed, replaced, or serviced by simply removing the flap from the remaining portion of the aircraft wing.
 5. In combination, an elongated waveguide antenna; an aircraft having a wing landing flap control surface movable from a first to a second position when approaching for a landing; means mounting the antenna on the aircraft in such a position that the beam pattern from the antenna is directed forwardly generally towards the horizon and downwardly from the horizon only when the flap is in a lowered position during a landing approach; and means for passing electromagnetic energy into one end of the waveguide antenna when the flap is lowered during a landing approach, said waveguide antenna having a series of holes dimensioned below cut-off so as to be non-resonant in a broad side wall to one side of the central line of the wall and a metallic flange portion extending normally from the edge of the broad side wall adjacent to the holes, said flange having a roughened surface to narrow the beam pattern in a plane perpendicular to the axis of the waveguide. 